The conventional electronic key telephone as disclosed by U.S. Pat. No. 4,164,630, has the capability to memorize and automatically dial many telephone numbers. In the memory, a telephone number is generally abbreviated as a two-digit number to represent the original number. However, if many numbers have to be memorized, three digits may be used. An index device is used to record the relationship between the original telephone numbers and their corresponding abbreviated numbers. The index device may be directly provided on the face of the telephone set. Several index cards can be overlapped to reduce their volume. Several selectors can be provided, each corresponding to a specific index card. When dialing a desired number, one first moves the card-selector to select a specific index card and then locates the desired number from that index card.
The present inventor has found many defects with the conventional apparatus. The present multi-purpose telephone set avoids many of the disadvantages of the conventional telephone index apparatus designed for automatic dialing.